If you own and use an ebook reader, can you recommend which one you like please? Have you tried more than one?
If u are a windows user and want to use a very lite pdf reader, i suggest you to download Sumatra PDF reader - http://blog.kowalczyk.info/software/sumatrapdf/index.html Its a very simple PDF reader, though i would prefer Adobe reader always.. Oh.. got it. U need a physical reader.. why not try out the Kindle 2 reader by Amazon?
I use iSilo on my old Palm and iPAQ PDAs. I do pretty much all my reading on my iPAQ these days. Unfortunately, reading PDFs doesn't work very nicely on a PDA - I've tried Adobe's pathetic mobile reader and Foxit Mobile, both suck.
If all you want to do is read eBooks, then have a look at the old Palms. Palm OS is great, and most of the old Palms have pretty nice screens. You should be able to pick up a used Palm TE (or something similar) for next to nothing.